Uticaj oblika azota na rast sejanaca invazivnih vrsta Acer negundo L. i Ailanthus altissima (Mill.) Swingle

Abstract

Relativna količina mineralnih hraniva, posebno azota, najobilnijeg makroelementa, kao i distribucija amonijumovih jona u odnosu na nitratne, u zemljištima različitih ekosistema, određena je brojnim faktorima. Najvažniji su: temperatura i hemijska reakcija supstrata, organska materija, prisustvo alelopatskih jedinjenja, stepen oksigenacije i dr. Od sposobnosti biljaka da se prilagode ovim varijacijama, zavisi produkcija njihove biomase, ali i brzina širenja, na različitim staništima, uticaj na ekosistem i biodiverzitet. U radu je analiziran efekat usvajanja različitih oblika azota (NO3 - i N H4 +) na rast sejanaca invazivnih vrsta Acer negundo L. i Ailanthus altissima (Mill.) Swingle. Rezultati pokazuju da ishrana sejanaca ovih vrsta drveća azotom samo u formi NH4 + jona utiče značajno na smanjenje suve mase nadzemnog dela. Kod Ailanthus altissima za 62,5% suve mase nadzemnog dela i 66,7% površine lista, a kod sejanaca pajavca redukcija suve mase nadzemnog dela iznosi 89,5%, korena 81,2%, a površine lista 85,8% u odnosu na ishranu sa obe forme azota zajedno. Isto tako i ishrana samo sa NO3 - oblikom azota dovela je do statistički signifikantnog smanjenja mase nadzemnog dela i korena kao i površine lista kod pajavca dok je kod sejanaca kiselog drveta značajno uticala samo na redukciju mase nadzemnog dela pa se ova vrsta može smatrati tolerantnijom. Činjenica da obe vrste produkuju značajno veću biomasu ako je azot zastupljen u oba oblika može imati značaja kod kontrole njihovog nepoželjnog širenja ili kod njihovog mogućeg korišćenja u fitoremedijaciji.

Relative amounts of nutrients, especially nitrogen, the most abundant macro-element, and also the distribution of ammonium ions in relation to nitrate ions, in the soils of different ecosystems, are determined by many factors. The most important are: temperature, pH of substrate, accumulation of organic matter, presence of allelopathic compounds, degree of oxygenation, etc. The ability of plants to adapt to these variations influences their production of bio-mass, the rate of expansion in different habitats, and the impact on ecosystem and biodiversity. This paper analyzes the impact of different forms of nitrogen (NO3 - and NH4 +) on the growth of seedlings of invasive species Acer negundo L. and Ailanthus altissima (Mill.) Swingle. The results show that nitrogen nutrition only in the form of NH4 + ions significantly affects the reduction in shoot dry weight. Compared to the nutrition with both forms of nitrogen together, aerial parts of Ailanthus altissima were reduced by 62.5%, and leaf area by 66.7%, while Acer negundo seedlings had reduction in dry mass of aboveground part by 89.5%, root by 81.2% and leaf area by 85.8%. Nutrition with nitrate form of nitrogen led to a proportionally small, but statistically significant decrease in dry mass of aboveground parts and roots as well as leaf area of Acer negundo, while in Ailanthus altissima seedlings, it was only the mass reduction of aboveground parts that was significantly influenced, so it can be assumed that this species is more resistant to the lack of both forms of nitrogen. The fact that both species produced significantly more biomass when nitrogen was present in both forms may be important in controlling the spread of alien species, or in their potential use in phytoremediation.